The present invention relates generally to digital satellite communication systems, and more particularly to a method and system for removing snow, ice and frost from the satellite receiver dish antenna upon detection that the received signal is degrading under conditions conducive to snow, ice or frost accumulation.
Generally, in modern digital satellite communication systems, a ground-based transmitter transmits a forward-error-coded uplink signal to a satellite positioned in a geosynchronous orbit. The satellite in turn relays the signal back to a ground-based receiver antenna in a separate location. Direct broadcast satellite ("DBS") systems allow households to receive television, audio, data, and video directly from the DBS satellite. Each household subscribing to the system receives the broadcast signals through a receiver unit and a satellite dish receiver antenna.
In the typical DBS system, the satellite receiver antenna includes an e.g. 18-inch parabolic dish and a low noise block (LNB), and the receiver unit may include an integrated receiver decoder module (IRD). The receiver antenna is typically mounted outside the house, and cables are provided to link the LNB to the indoor IRD and associated equipment (e.g. video display).
Several factors can degrade received DBS signals. For example, the satellite receiver antenna can accumulate snow, ice or other debris unseen by the user. This accumulation can degrade the received signal strength enough to interrupt IRD operation. This may be a particular problem in colder climates where seasonal snow, ice or frost accumulations can degrade the performance of an antenna reflector and/or an LNB, particularly in the Ku band or other high frequency bands utilized by many present DBS and terrestrial systems. Furthermore, due to the significant amount of forward error correction used, the DBS picture quality may not suffer any noticeable decrease although signal strength is continuously degrading. When signal strength falls below a certain minimum, the signal can be completely lost without warning.
Therefore, there is a need for an inexpensive and simple method and system for automatically detecting a degraded signal and clearing snow, ice or frost from a home receiving antenna. There is a particular need for such a system which can better determine when a corrective response for snow, ice or frost accumulation is appropriate, by discriminating between signal reductions caused by these events as opposed to other possible environmental causes such as rain fade.